1. Technical Field
The present invention relates to a light source device, a lighting device, a projector, and a monitoring device.
2. Related Art
Recently, a coherent light source is an essential unit in the fields of image display apparatus, optical communication field, medical field, and measuring field such as microscope, and wavelengths of the coherent light to be used in these fields vary according to the purposes of use.
Thus, a wavelength converting element which utilizes non-linear optical effect and capable of expanding use wavelength range of a laser beam source by wavelength conversion for converting wavelength of light is currently used in a number of fields. According to the wavelength conversion of light utilizing non-linear optical effect, phase matching condition needs to be established between fundamental waves before conversion and higher harmonic waves after conversion. Thus, quasi phase matching method which periodically reversing polarization direction is used. More specifically, wavelength converting element (periodically poled lithium niobate (PPLN) which achieves quasi phase matching (QPM: quasi-phase-matching) by forming periodical polarization reversing structure on LiNbO3 is used (for example, see JP-A-2006-332447).
A laser beam source device disclosed in JP-A-2006-332447 has a plate-shaped support base on which various components of a laser beam source unit are mounted. A PPLN folder is provided on the support base via a spacer for limiting the attachment height of the PPLN folder.
In case of optical components such as PPLN, performance is variable according to the entrance position of light. Thus, light needs to enter the optimum position.
According to the laser beam light source device shown in JP-A-2006-332447, the positions of the various optical components such as PPLN are not fixed to the support base, but are controlled relative to the light source. In this case, the conversion efficiency of the PPLN lowers, and the utilization efficiency of light entering the various optical components decreases.
Further, when alignment of the various optical components such as PPLN relative to the light source is carried out with the configuration, additional components for adjusting the positions of the optical components are required whereby the working efficiency lowers.